Process of finishing printing plates



May 31, 1938. w. H. BA NZETT 2,118,301

PROCESS OF FINISHING PRINTING PLATES Filed Aug. 13, 1937 Fla 1 F/4/6 l lINVENTOR.

Mi/l/am l7! Banze/f W I ATTORNEY Patented May 31 1938 I I I 2 11 01-UNITED ,STATES- P TENT err-ice raocsss or rnhzi lis zimmnrorm'rss wuu'mn. migflifhn. N. .r. Application A II III M'IS, 1937, MINI). 158,943

I .1 (cl, Ill-401.3)

The purpose of this invention is to improve of backing metal is shavedoil, and the plate is the method of finishing the printing surface orthen trued upto the face again, and shaved irem. face of printing platesto eliminate all irreguthe back. I I larities and unevenness in theprinting or con- After all of these manipulations are completed tastingsurface of characters or type thereof.. 'at great expenditure of timeand labor, the ac-- d The invention is the art or process of planlng,curacy is really dependent on the skill of the grinding or lapping theprinting surface or face operator. of electrotype, stereotype, or othertypographic It can readily be seen that a short or i or raised characterprinting plates, which may be displacement of the type face cannot becomflat or curved in order to provide absolutely true pletely correctedfrom the back of the plate. or even contacting surfaces of the type,charac- In the case of stereotypes the same lockup is ters, or the like,thereof, and, at the same time, pressed against a wet paper mat-', andheat is providing an absolutely true, flat or cylindrical applied to themat from the opposite side until finished surface. the paper is dry andhard. 'I'hismat then forms W The irregular height of type faces onduplia face mould into which melted stereotype metal ll cated or moldedprinting plates requires consideris poured to make the complete plate,either flat able make ready work, and padding of both the or curved, thetheoretical curves actually provmounting for the plate and also of theimpression ing a series of chords approximating a circle, as surface orcylinder, and, although metal has been the face of all characters isoriginally flat.

planed from the back of the plate, it still leaves Inaccuracies ofvarying thickness of mat", w irregular type faces or printing faces.-distortion of original lockup and pressure while The individual typecharacters or linotype being heated, and distortion while the hot metalslugs, rules, borders, etc., are locked in a chase. I is being cast, allcontribute toward errors and The chase itself is a surrounding body atright irregularities.

angles to the clamping means. This is then set Various ways of bendingthe electros to cylinupon a "stone, a smooth level surface,'and alldrical form after shaving approximately true are characters or lineslugs are beaten or hammered used, and "hot forming fixtures" areapplied to from the back so as to try to get the printing try to gettrue curved plates. Another type of face in a true plane, but this isalmost impossible printing plate is made by moulding plastics such llas, as one section is beaten down, the other secas bakelite into amould, and as this mould is tion slips a little, etc. made fromtype,1ocked up in a chase, the irmu- For'an electrotype this locked uporiginal, or larities are also present. master form, is pressed into waxto get an im- All of these irregularities must be corrected in pressionin reverse of the type face and the wax a manner knownto the tradeas"make ready" on St impression is black leaded to give it a metallic thepress, which is a slow costly operation as an as conducting surface. Itis then suspended in an expensive press is idle during this time. It iselectrocopper plating solution, and by electrotherefore desirable toeliminate a large portion deposition, a copper shell is deposited on thewax, of this "make ready time that ties up the expenusually from .006"to .010" thick. This shell is sive press, and, at the same time, improveor so stripped from the wax, cleaned in .various ways, perfect theactual contacting printing face of M and the back face is tinned bymelting tinfoil Y the type or plates. I over the copper so that theheavy type metal The object of this invention is, therefore, to backingwill adhere to the shell when it is poured eliminate all irregularitiesin the printing face of into it in a molten state. type, and, at thesame time, provide plates, the

5 The stripping of the copper shell from the wax, printing surface ofwhich is parallel to the back the "tinning and applying the hot backingmetal, so that the distance through the plate is equal all distort theprinting face from its original at all points, and, particularly incylindrical printnearly true plane. It is then placed upon a true ing,the plate may be mounted upon a true cylinsurface and again beaten fromthe back to try der without underlays, so that the make ready" to bringthe printing face to a true plane. time is reduced to a minimum oreliminated. so

There are various ways of doing this, either Another object isto providea method of commanually or by mechanical means, but they all pensatingfor unevenness of single characters, have the final objective of tryingto get all type such as a bold letter I, by grinding oil the ends, facesto a true plane. I 1 making the'surfaceof the letter in an arc in- Afterthe faceis approximately true, the excess stead of a straight line,thereby making it pos- I8 sible obtain an even impression throughout thelength thereof.

A further object is to provide an improved method for finishing theprinting surfaces of printing plates, in which the plates may befinished, ready for use, on a separate machine, and then readily mountedupon a printing cylinder, in which the printing cylinder may beperfectly round without the use of underlays or the like.

A still further object is to provide'an improved method for finishingthe printing faces of printing plates, in which the contacting surfaceforms an absolute cylinder, eliminating the necessity of overlays on theimpression cylinder to compensate for irregularities as is normally thecase.

And a still further object is to provide an improved method of obtainingan absolutely even contacting or printing face of printing plates ortype, which is relatively simple and inexpensive.

Other features and advantages of the invention will appear from thefollowing description taken in connection with the drawing, wherein:

Figure 1 is a diagrammatic view showing a printing plate with unevencontacting or printing surfaces of characters or type thereof, greatlyexaggerated in order to illustrate an actual condition.

Figure 2 is a similar view with theunevenness also exaggerated showing acurved plate.

Figure 3 is a view showing a printing plate mounted upon a grindingmachine, in which the grinding machine is incomplete, and only used forthe purpose of illustration. Y

Figure 4 is a. view showing a method of attaching a printing plate tothe surface of a cylinder for grinding the face thereof.

The electrotype, stereotype, or plastic printing plate is made in theusual manner of the art as accurate as good trade practice demands, andthis plate is mounted with its finished back on a true surface, either aflat or curved plane. In order to true up the printing surface or typeface, metal or material is removed from the face in what may be termed asuper refining process, preferably on a separate machine, and, althoughthe parts are shown exaggerated in the. drawing, it will be understoodthat only a few onethousandths of material are removed, however, withthe ordinary printing plate this is sufficient to provide an absolutelytrue surface. On very slender type this requires a very fine grindingprocess, or a lapping process, and, when'flnished, the thickness of theplate, or the distance frpm the face to the back is absolutely equal atall points.

In the drawing a fiat printing plate is indicated by the numeral I, andthis is placed upon a stone 2 having an absolutely true face or exposedsurface 3, and it will be noted that the type or characters of the plateI engage the face 3 at a plurality of points, and if these faces weremachined off, all of them would rest against and engage the surface 3.These faces are conwould be very difficult, and it would also be verydifficult and practically impossible to line up a bevel surface such asthat of the type indicated by the numerals I and 8 without damaging theprinting face. With any process used up to the present time, whichinvolves forcing the type from the back of the plate, it issubstantially impossible to obtain an absolutely true printing face, sothat it is necessary to pad the impression plate or cylinder, and alsouse considerable padding behind the printing plate.

Another plate is shown in Figure 2, in which the plate I has been formedaround a curved or cylindrical surface, and it will be appreciated thatin bending the plate the hard type surface upon a cylinder I3. and thecylinder is mounted on a shaft H in bearings IS on a base l6, and

a grinding wheel I! is mounted on a traveling carriage l8 and rotated bya motor 19 through a belt 20. It is understood that this is only atypical arrangement, as the grinding wheel may be mounted and operatedin any manner or by any means.

In Figure 4 the plate 9 is shown attached to the face of the cylinder I3 by clamps 2i, however, it will be understood that this plate may bemounted upon the cylinder, or upon a flat plate or any means in anymanner or byany means. It will also be understood that any means may beused for surfacing the exposed surface, or turning, grinding, or lappingthe surface in order to remove all unevenness or irregularities, and

this may be accomplished by machine or any means.

Thisoperation or process provides a printing plate with a true fiat orcurved surface, and that is of equal thickness from the printing face tothe back at every point, and, as the final finishing may require theremoval of different amounts of metal or material from the face of theplates, each plate will be of an even thickness in itself, however, oneplate may vary from another of the same set, and the plates should,therefore, be prepared by refinishing the back or inside to apredetermined thickness, or various uniform thicknesses of sheets ofmaterial, such as paper, may be added to the back to compensate forvarying finished thickness in order to make the total thickness of allplates equal.

Lapping or finishing the face of the type in this manner also providessharp edges, so that even worn electrotypes, or any typographic plates,could be relapped or refinished to bring up sharp printing instead ofreplacing plates with new ones on long runs. a

It will be understood that changes may be made in the process withoutdeparting from the spirit of the invention. One of which changes may bein the use of any other type of machine or mechanism for holding theplate while being lapped or finished, another may be in the use of anyother process for removing material from the face of the type or plate,and still another may be in the use of this process for obtaining a trueprinting surface on devices for any other p p The process or operationthereof will be readily understood from the foregoing description, andit will be understood that plates finished in this manner will providean absolutely true even printing face or surface, and it will be of eventhickness throughout, and may be used on true or the like on theprinting face, and of the type made from a master mold; which comprisesmounting said plate upon a true base and removing material from theprinting face thereof to correspond to said base, the distance from thea printing face to the back of the finished plate being equal at allpoints.

Wm H. BANZE'ITY

